I thought about this more and actually only certain panel strings are tied to each inverter, so if one inverter goes down it will limit your system. Maybe that’s just my system design but I don’t think you can tie all strings to one inverter? Maybe I’m thinking about this wrong and am incorrect…
Ok so I was halfway there lol. It is still good to have two PW+'s with two inverters bc as like you said, if one inverter goes down your whole system doesn't go down (like many on this forum have had with a bad inverter and only one PW+). Thanks for the info
Lots of things come into better focus from observing system operation vs energy useage habits. Since going into operation last June I've done several things to reduce household useage. Easily the biggest step was replacing a straight electric water heater with a heat pump water heater. I've also gained the ability to car charge on excess solar. I had already gone to a higher efficiency heat pump in 2018. My useage in the first year of operation (nearly 10 months in) is trending toward a 27% reduction from the preceeding 12 months. Haven't started into my refrigeration/freezer (2/3) consolidation or heat pump dryer replacement yet, it's higher hanging fruit. Looking like I'm heading toward producing 75% of my useage annually, 6-7 months of self powering.
3 PW2 have gotten me thru a 3+ day grid outage with low generation (heavy clouds). But, I already am thinking adding more PW would be good. 2gets you over the threshold of whole house backup, 3 lets you get to the middle of that space, but 6 can actually get you real close to claiming off grid capability if you've got sufficient generation.
Which heat pump water heater did you get? Since I am in a brand new house (2023 build) it obviously doesn’t make sense to replace the HVAC heat pump, although it is SEER 15 so not awful anyways. However, I was thinking of getting a heat pump water heater even though my water heater is also new with the house. I wouldn’t mind paying for a new heat pump one though since there are ample tax credits and rebates to offset the cost also. This seems to be the next biggest use of electricity I have, especially in the winter and especially since my wife loves a hot shower lol.
Why I love my 7 PW's. I can basically go off grid for like half the year
I have a very regular house: 2250 sq ft, 2 stories, all electric, and it’s just my wife and I, no kids so not much hot water use and not that much cooling/heating space, relatively speaking. I still can’t fathom going off grid in the winter. I’m still waiting install (see signature) but PVwatts tells me I’m not getting more than -900 kWh max monthly production in the winter with my 9.315 kW DC panels facing almost directly south (roof space maxed out too). I’m in SC for reference, so not super south like Florida but certainly not mid atlantic or north either for solar production. I used 1500 kWh last December with my thermostat at 68 degrees and also with being gone for a week for the holidays. I just don’t see how you can go off grid unless you have a massively oversized solar array, which may need to be ground mounted as roof space becomes an issue, and like you said 6-8 PW’s. So I’ll be self sustaining in the spring and summer likely, but certainly not in Dec-Feb.
To save more energy, I think that you will like a heat pump model, but I would ask how close the water heater is to sleeping spaces. They are noisier.
My water heater is in my attached garage, but it is an unheated/cooled space. It stays warmer than the outside though due to 2 of the 4 walls being conditioned space on the other side, as well as the ceiling which has the master bathroom above. How much warmer it stays is an open question as it does get at or below freezing here in the winter.To save more energy, I think that you will like a heat pump model, but I would ask how close the water heater is to sleeping spaces. They are noisier.
You might want to double check the energy use on that dryer; is it a pure heat pump or a hybrid model? Whirlpools aren't terribly efficient compared to some others. The best Whirlpool is about half of what Miele and LG offer, though granted about half of a regular dryer.
Product Finder — ENERGY STAR Certified Clothes Dryers
Compare ENERGY STAR Certified Clothes Dryers, find rebates, and learn more.www.energystar.gov
All the best,
BG
Do you have a "blanket" around the water heater. In your case this would likely help with efficiency quite a bit! Something like this:
I got an A. O. Smith 60 gal hybrid water heater. It connects to your existing 30A 240V circuit, and you can run it in 3 modes, resistance heater elements only, hybrid, or only heat pump. Hybrid runs heating elements some if you run the hot water out. It's got an app for IOT control. It's been great. I just keep it in heat pump mode. Makes any resistance element heater look like a pure energy hog in comparison. If your water heater ismin an unheated space, you should consider a blanket like GateFather suggests I would think. And consider hybrid mode on a heat pump water heater for winter season.
I would be right there with you if I added another 2-3 PW. I'm really am now, but that 3 day outage in early August with low solar generation made me sweat a little.....
Even a water heater in a conditioned space is significantly warmer than the area around it, and thus the water heater does have significant energy losses. I think that every water heater should have an extra insulation blanket on them. The blankets are cheap, installation is straightforward and the payback time is very, very short.
Following back up as I researched this more. According to energy star, the Whirlpool vented electric dryer I got last year will use 608 kWh per year vs 460 kWh for the heat pump ventless version Whirlpool makes, which apparently is part of the energy star “most efficient” list. 148 kWh annual savings doesn’t seem worth it to me.To save more energy, I think that you will like a heat pump model, but I would ask how close the water heater is to sleeping spaces. They are noisier.
You might want to double check the energy use on that dryer; is it a pure heat pump or a hybrid model? Whirlpools aren't terribly efficient compared to some others. The best Whirlpool is about half of what Miele and LG offer, though granted about half of a regular dryer.
Product Finder — ENERGY STAR Certified Clothes Dryers
Compare ENERGY STAR Certified Clothes Dryers, find rebates, and learn more.
All the best,
BG
Why would you say that? You only heat the water you use, instead of the water you use plus keeping it hot 24hrs a day. A quick search on Google for "energy used water heater 50 gal vs. tankless" shows a 30% avg savings with a tankless.
